Contact and aeroallergens in adulthood atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a clinically well-defined, chronic-intermittant, genetically predisposed skin disease. The increasing number of adult cases observed in the last years has turned the attention to ascertaining factors eliciting skin symptoms. Studies have revealed numerous environmental components (e.g. contact and aeroallergens) that may play an important role in sustaining the symptoms. The aim of the study was to search for contact allergens and aeroallergens triggering the skin disease in adult AD patients.

METHODS: Patients over 18 years from our Atopy Outpatient Department were included in the study. Diagnosis of AD was based on the clinical criteria of Hanifin and Rajka. The distribution of skin symptoms was characteristic for adult AD: hands, shoulders, neck, flexures, face and eyelids. The extremities and the trunk were less involved. The potentially provoking contact and aeroallergens were examined in symptom and drug-free period with atopy patch and epicutaneous tests (APT, ET), which were supplemented by in vitro allergy and Prick tests. The relevance of sensibilization was evaluated by the comparison of in vivo and in vitro test results, medical history and skin symptoms.

RESULTS: A total number of 34 cases of adult AD (23 women and 11 men) were studied. Four of them were classified into the intrinsic group (IG; 12%), and 30 were classified into the extrinsic group (EG; 88%). The incidence of contact sensitization to environmental allergens was remarkable: 13 of the EG, 1 of the IG (14 of 34, 41%). In the IG, a late thiomersal positivity was detected without clinical relevance. In the EG, epicutaneous standard series late positivity was seen in 13 patients, in four of them with multiple sensitivity. The allergens causing positivity were nickel (6 of 13), thiomersal (3 of 13), mercury-amidochlorate (3 of 13), mercury-chloride (2 of 13), iodine chlorhyrdoxyquin (1 of 13), lanalcolum (1 of 13) and fragrance mix (1 of 13). Among the detected allergens, the following were relevant: lanalcolum (1 of 13: cosmetics), fragrance mix (1 of 13: cosmetics), nickel (1 of 13: metal objects), thiomersal (1 of 13: eyedrops). No immediate response was seen with APT. Relevant late positivity was shown with APT test in one patient in the IG (1 of 4) to Dermatophagoides pteronyssinus. We observed late positivity in 18 patients in the EG (18 of 30). Among the detected allergens, the following were clinically relevant: D. pteronyssinus and/or Dermatophagoides farinae (15 of 18), cat epithel (4 of 18), timothy pollen (1 of 18) and dog epithel (1 of 18). Furthermore, we examined the relevance of APT, specific immunoglobulin E (IgE) tests and Prick tests. We observed multiplex positivity by specific IgE tests, APT and Prick tests in 14 patients in EG. Sensitization to D. pteronyssinus and/or D. farinae (11 of 14) cat epithel (4 of 14), dog epithel (1 of 14) and timothy pollen (1 of 14) proved to be clinically relevant with the atopic skin symptoms and medical history.

CONCLUSION: The proportion of contact sensitization to environmental allergens in the 34 adult atopic patients was remarkable (14 of 34, 41%). Out of the verified contact allergens, nickel, fragrance mix, thiomersal and lanalcolum proved to be relevant. House dust mite and cat epithel proved to be the most common relevant aeroallergens. D. pteronyssinus and D. farinae sensibilization was high, particularly in patients with severe skin symptoms on the face, eyelids and hands. Pollens should be considered in patients with seasonal relapse of AD. Sensitization to animal epithel was usually indicated by the flare-up of skin symptoms upon contact with animals. The relevance of the eliciting effects of sensitization could easily be supported in most cases by the medical history and the distribution of skin symptoms. In some adult AD patients with long-lasting AD, the relevance of triggering factors is hard to determine.